This invention relates to the reception and acquisition of data transmitted in conjunction with a video signal. In particular, it relates to the detection and acquisition of data transmitted in conjunction with a video signal in a cable television environment wherein the data may, among other things, determine the authorization to a particular television channel associated with the cable transmission.
In the cable television environment, the cable transmitting station generally makes available to the customer a family of programs that are transmitted simultaneously over the cable to the individual customers' television sets. At the individual customer's television set is a cable interface that enables the customer to select the desired channel. The interface or tuner "tunes" the selected cable channel to the customer's television set for display on a commercial television channel. In the United States, a commercial television set is tuned to either channel 3 or channel 4 in the VHF range to receive the cable signal. The channel tuner, therefore, makes available to the television set on either channel 3 or 4 the selected programs transmitted over the cable. Cable television services can simultaneously provide to the user fifty or more channels.
It is common among the cable television systems to provide various tiers of service. Each tier of service may include the lower tiers by adding to the lower tiers one or more additional programs or types of programs. For example, the lowest tier generally includes the local standard channels in the area being covered by the cable service, usually along with a community service channel that provides coverage of the local governing bodies and any other community program considered appropriate.
A higher tier could include an exclusive sports channel while still another tier could include recently released motion pictures. The customer could subscribe to the lowest tier and one or more of the higher tiers at its option. It is to be understood that a change in the level of programming or tier of programming selected usually changes the monthly service charge to the customer.
Recently, cable television systems have started to provide "pay as you view" service for special events such as world championship boxing bouts, and prospectively such events as quadrennial Olympics. It is envisioned that in the near future, first-run motion pictures will be made available to cable television subscribers on a "pay as you view" basis at the time of release. In the "pay as you view" environment, the cable service must have the capability to "turn on" and "turn off" the authorization to view a particular special program. Furthermore, the cable television service should have the capability to change the tier level of a particular customer at will. Finally, for those customers that fail to keep their payments current, the cable service should have the capability to "turn off" the service to that particular set. In the crudest sense, this capability can be provided by sending a technician to the individual's home to (1) authorize a special showing; (2) change the tier level of the channel tuner; or (3) disconnect the cable from the television set.
On the other hand, the subscriber, in receiving the cable signal, would very much like to be able to request a particular special event or tier level up to the time of transmission of the event. Similarly, the customer, in the event he or she is prevented from seeing the show or special event, would very much like to cancel the requested authorization up to the last minute in order to save the "pay as you view" charge.
Since each television cable system supplies a vast number of users (for example, 10,000), it is incumbent upon the individual cable system to be able to communicate with the channel tuner and associated circuitry to "turn on" and "turn off" special events and set tier levels from the head end or transmitting station. Generally, this may be accomplished by separate channels or by rather slow serialized data transmission tuned to the reception rate of the unit controlling the individual television set. The result is the user may not be able to obtain authorization for a special program at the last moment. Further, if authorization is obtained on a particular channel, the user may be able to immediately disconnect the tuner following the special event so that the authorization remains in effect until the next special event is scheduled. This is possible because the deauthorization signal, which must also be transmitted over the cable system, may not come at a sufficiently close interval to ensure the user only obtains access to one special event or does not extend authorization for a particular tier level beyond that which has been paid for.
The principal reason for the slowness of data reception is that cable systems have been required to transmit individual messages to the various users in a serial fashion. Thus, the message to user 1 is immediately followed by the message to user 2 until all of the messages have been sent out to the various users among the 10,000 plus cable customers. Furthermore, if the data transmission rate is too fast for the microprocessors located in the home unit, the data may simply not be received. In order to overcome this, cable data systems must slow the data transmission rate to be compatible to the more reasonably-priced microprocessors. In slowing down the data transmission rate, the repetition rate for the authorization signal and the deauthorization signals is markedly reduced. While slowing down the authorization rate has no immediate adverse affect on the cable system other than customer dissatisfaction because of failure to obtain authorization, slowing down of the deauthorization repetition rate may result in lost revenues when customers are able to tune in on two or more special events after having ordered and paid for only one.
The capability to transmit data at a relatively high rate over a cable system would permit a cable system to provide other services to the user, such as video games, billing information, or to display coming events. For example, in order to play a video game, the customer would "order up" the video game to be played on the home television set by telephone or on a keyboard associated with the cable tuner. The game, once authorization had been received, would be transmitted to the home video set and would be available for play for a specified period of time, such as one-half hour or one hour, at which time authorization would cease and the game would be stricken from the customer's microprocessor memory. Existing cable television systems do not have the capability to transmit the game program in a sufficiently short time to make such an operation feasible.
In addition to "pay as you view" authorization and the video game capability, existing systems do not permit the transmission of "real time advertisements" for overlay on a video picture. For example, if a cable system has programmed a special event such as a world boxing championship bout for the following night, it would be appropriate to announce to the viewers that access to this bout may be obtained by dialing the cable television system and asking for the authorization to watch such a bout. Such advertisement would be provided to the subscribers or customers by means of a data channel directed to each and every cable subscriber for overlay on the television set while the television set is tuned to one of the normal programs made available by the television system.